Conventional drives for devices for lifting a hood may comprise an energy storing unit, which drives an actuating member of a lifting mechanism coupled to the hood, an electromotor, by which the energy storing unit can be set into a tensioned state, and a locking element which in a rest position holds the energy storing unit in the tensioned state.
The protection of pedestrians in motor vehicles can be improved in that in a collision of a pedestrian with a motor vehicle, the hood is lifted in order to increase its distance from solid frame parts or engine parts. The kinetic energy of the pedestrian can be reduced by suitable deformation elements. Various drive designs are known for devices for lifting a hood. The essential requirements of such a drive are rapidity and reversibility. These requirements can be fulfilled at the most favourable cost with energy storing units which can be re-charged several times.
From published European patent application EP 1 179 458 A2 a reversible drive is known, in which a spiral spring can be tensioned by means of a reducing gear unit of an electromotor. If the reducing gear unit is brought into a release position by the motor, the hood moves abruptly into a lifted position by the released energy of the spiral spring.
It is an object of the invention to provide a drive which enables a rapid lifting of the hood, which can be transferred with minimum effort into its initial position again by the driver, and which is distinguished by a simple construction and a favourably priced installation.